Marner, as far as I'm aware, doesn't have kids.
That being said, you look at the approach taken by these 3 in all of their contracts, and the theme of "setting a new high bar" has always been prevalent.
Giving Nylander the 2nd contract richer than Pastrnak's was highly unjustifyable at the time. The fact that they let him skip the first half of the year, and monkeyed with the money so he still got paid in full, even more ubsurd.
Then comes Matthews, who could justify that he's worth more than Eichel and less than McDavid, but conveniently left off 2 of the most valuable years of those deals. For this season & next, he'll be paid more than McDavid, and had COVID not happened with the cap being flat for 5 years, he'd have probably been looking at $14m+ to McDavid's $12.5m.
Then comes Marner, who as a winger pushes the Leafs for $10.893 (that then gets boosted because they didn't consider league min salary going up) on just 6 years... meanwhile Rantanen doing the same things he is, signs for $9.25m.
The Leafs had an opportunity to try and "correct course" with this last round of negotiations. It should have started with giving Nylander an ultimatium of $9m or trade... yet they refuse to do so, and again, inexplicably, paid him more than his buddy David Pastrnak, who literally carries Boston offensively.
I don't think there's any way you're going to convince Marner to take $9-10m when he just watched his 2 buddies cash in on ridiculous deals... especially given all the history of wanting to set a new benchmark.
He'd have to have a real "change of stripes" in terms of prioritizing being a Leaf and having a chance to win, putting his ego aside.